body>div {
    width: 50%;
    height: 50%;
    margin: 100px auto;
    background-color: pink;
    padding: 40px;
}

.goTop {
    position: fixed;
    right: 50px;
    bottom: 50px;
    width: 100px;
    height: 100px;
    line-height: 100px;
    text-align: center;
    background-color: aqua;
    border-radius: 10px;
    font-size: 22px;
    font-weight: 600;
}

.active {
    color: #f70;
}

/* 测试git提交工具sourcetree */